Thread-cutting die



Jan. 8 1924. 1,480,036

F. o. WELLS ET AL THREAD CUTTING DIE Filed March 22 1921 INVENTORfi, flan/Z a. It Z'lk, BY ZkwidBJ flier.

A TTORNEY.

Patented Jan. 8, 1924.

FEE.

FRANK O.- WELLS AND DAVID B. MILLER, 01! GREENFIELD, MASSACHUSETTS, AS- SIGNORS TO THE WELLS CORPORATION, OF GREENFIELD, MASSACHUSETTS, A COR- PORATION OF MASSACHUSETTS.

THREAD-CUTTING DIE.

Application filed March 22, 1921.

To all whom it may concern.

Be it known that we, FRANK O. TELLS and DAVID B. MiLLER, citizens of the United States, and residents of Greenfield, in the county of Hampden and Commonwealth of Massachusetts, have invented certain new and useful Improvements in ThreadCutting Dies, of which the following is a specification.

This invention relates to improvements in metal cutting tools, and more particularly to screw or thread cutting dies for forming a thread on the outside of a circular piece of material, as a rod, bolt, pipe, or the like.

An object of the invention is to provide a thread cutting tool in which a plurality of lands or prongs are provided having the thread forming teeth thereon, which are so constructed and arranged that the chips, or removed metal, will be directly carried away from the thread during the cutting operation, thus preventing the tool and removed chips from injuring, or in any way destroying the efficiency of operation.

A further object is to provide a thread cutting die so constructed and arranged that there is no possibility of the tool springing or becoming distorted in a circular direction during the thread cutting operation. In other words, the tool is made sufiiciently rigid and non-elastic as to prevent spring ing or distortion. Heretofore it has been a common practice to mount a thread cutting die in suitably formed holders to avoid the possibility of the lands of the die becoming distorted, either in a radial or circular direction.

A further object is to provide a die in which the cutting edges will operate so as to produce a shearing or drawing action, similar to the operation of a chisel or drawshave knife when held at an angle to the line of motion in order that the material may be removed with the least possible expenditure of power, and whereby not only is a better thread produced, but the thread forming tool, or die, will be capable of greater endurance or length of service before it is considered worn out.

Referring to the drawings:

Fig. 1 is a plan view showing the die in operation, and illustrating the manner in which the removed material leaves the work.

Fig. 2 is a perspective view showing the Serial No.- L400.

die removed from the work and illustrating the construction of the prongs or lands.

Fig. 3 is an end View looking along the anial line and directly into the die. This view clearly illustrates the inclined or angular position of the lands, also the recessed portion directly back of the cutting teeth.

Fig. 1- is a sectional View on the line l-t of Fig. 3 looking in the direction of the arrows, showing the inclined position of the lands and chip receiving recess.

Referring to the drawings in detail: 1 designates the body part of the tool in the outer surface of which is formed the longitudinal channels or grooves 2 to receive a suitable holder, as a chuck; 3, at, 5, and 6 designate the four thread cutting prongs or lands having the teeth 3', 4t, 5, and 6 formed on their inner curved surfaces. L0- cated and formed immediately in the rear,

or at the ends of the cutting teeth, are the longitudinal recesses or depressions 7 in order to provide'proper and sufiicient clearance to prevent the apex or crown of the finished thread on the work 7 from being injured or roughened. In other words, the finished thread will not drag on the cutting teeth of the prongs.

A further important feature of our improvement is the location of the advancing or cutting surfaces 8, 9, 10, and 11 of the prongs 3, 4-, 5, and 6, in a plane that stands at an angle to the axis of the tool. This construction has the effect of removing the material similar to a chisel or draw-shave knife when held at an angle to the line of motion. This angle may be shown by the dotted line 12 (see Fig. 4), which is a prolongation of the advancing or cutting edge of one of the prongs, indicated at 13. 14 designates in dotted lines a plane coinciding with the surfaces 8, 9, 10, and 11, which passes through the axis of the die and work (see Fig. 3), whereby the advancing or cutting edges are in planes passing through the axial or center line of the die. It is, of course obvious that these planes may be arranged in advance or ahead of the center, depending upon the kind of material being operated. upon. It will also be observed that the planes of the advancing surfaces 8, 9, 10, and 11 are inclined slightly rearwards in addition to the angle 13, similar to the manner of tipping the blade of a knife when removing a shaving or chip. These surfaces are inclined atan angle to the surface of the work on which a thread is being cut, and not at right angles thereto.

The die, therefore, removes the material indicated in Fig. 1 at 15, by means of ad vancing cutting planes or surfaces that stand in planes that are at an angle to the line of motion (see 13, Fig. 4), and also at an angle to the work, as shown in Fig. 3, at 14.

It isto be understood that the prongs are made sufiiciently rigid at their basesso as to prevent any spring or distortion in a circular direction during the cutting operations." The rigid construction is indicated by the line 14. In use the die is placed in a clamping chuck or holder device in order to guard against any undue distortion of the prongs radially, and also to accurately adjust the 'diametral distance of the cutting teeth with relation to each other,

In operation the die may move'or travel in the direction of the arrow shown in Fig. 1, andthe work is held stationary, or both the die and work may be rotated, as desired.

The metal which is removed is carried di rectlyoutward and forward of the die, as shown, thus preventingthe removed metal orchips from coming into contact with the finishedthread. Theteeth a-t the' advancing end serve to formthe thread on the work, while those at the rear portion serve to accurately guide the cutting tool.

1 ,a-eopee 7 through, a plurality of tapered prongs each formed with thread forming teeth, and recessed portions-immediately in the rear of each of the teeth of the prongs.

2. A; thread cutting die formed with a plurality of cutting teeth located on separate lands, each land being formed with a curved recessed part back of the cutting teeth to provide a clearance space for the finished teeth, the plane of the advancing or cutting face being at an angle to the work upon which a thread is being cut.

3. As an article of manufacture, a thread forming die having non-resilient prongs with thread cutting teeth thereon, the advancing or cutting face of the prongs being arranged at an angle to the axis of the article, and also in a planewhich is slightly inclined rearwardly to the work.

4. A thread forming die comprising a one piece member having a plurality of prongs, each prong having a row of thread forming teeth that are arranged at an angle to the axis of the die, and each row having an arc-shaped recess which is located between the real-edges of the rows of teeth and-the forwarder advancing edges of the following row whereby the finished thread will be free from chips, as described:

FRANK O. VVELLS. DAVID BL'MILLER. 

